This invention relates to a solid-state radiation detector, particularly to one characterized by using a single crystal of the compound semiconductor InSb. InSb has the smallest band-gap energy of all the compound semiconductors known today and can create the greatest number of electron-hole pairs within the bulk upon irradiation, thus exhibiting better energy resolving characteristics than the conventional solid-state radiation detectors. Hence, InSb is used as an x-ray detector of high energy resolution in fluorescence x-ray analysis or in x-ray spectrometry at synchrotron radiation facilities. In addition, both In and Sb have higher atomic numbers than Ge which has heretofore been employed as gamma-ray detector, so InSb can be used as a gamma-ray detector for gamma-ray spectrometer having high detection efficiency and high energy resolution.
The Si(Li) or Ge detector featuring comparatively high band-gap energy has heretofore been employed as a solid-state x-ray detector with high energy resolution and the limit of energy resolution is about 120 eV in the case of measuring 6 keV x-rays.
Wm. C. McHarris pointed out in 1986 that the band-gap energy of the compound semiconductor InSb was so small (0.165 eV) that it had the potential to be used as a radiation detector [see Wm. C. McHarris, Nucl. Instrum. Methods Phys. Res. A242, 373 (1986)]. Although an InSb based infrared detector was later developed, it was not until recently that a radiation detector using the compound semiconductor InSb has been actually developed.
Kanno et al. recently fabricated a semiconductor device of the construction shown in FIG. 11 by forming a Mo surface barrier layer on top of a Ge-doped p-type InSb single crystal in order to provide it with diode characteristics. Kanno et al. also reported that the device could be operated at 4.2 K or lower temperatures in order to detect α-rays [see Kanno et al., Review of Scientific Instruments, Vol. 73, No. 7, 2533 (2002)].